Torchwood is reborn tomorrow night, as a big-budget co-production with the American cable network Starz. But with three seasons of this British science fiction show already out there, what do you need to know to enjoy it?

The short answer is: Absolutely nothing. The new series brings you up to speed pretty easily.

But there's still stuff that might make more sense if you know the backstory. Here's our complete guide to everything you need to know about Torchwood before Miracle Day.

Absolutely no spoilers for Torchwood: Miracle Day await you, but there are major spoilers for the first three seasons of Torchwood. Plus Doctor Who.

So you might have heard that Torchwood is a spin-off of Doctor Who, the BBC's flagship science fiction program which is closing in on its 50th anniversary. That's a lot of continuity to keep track of, right? Not really. The good news is, Doctor Who seldom pays attention to its own continuity, and Torchwood's links to the Whoniverse* are fairly small at this point.

The Torchwood Institute was founded by Queen Victoria back in 1879, to defend Britain from extraterrestrial threats - including the time-traveling Doctor himself.

Flash forward 120+ years, and Torchwood became a huge, powerful secret government organization that is prepared to take extreme measures to advance the British national interest. Until the organization was all but destroyed due to its over-reaching.

As a result of the events on Doctor Who, Torchwood was reduced to just one satellite office in Wales, which operated near a rift in the space-time continuum in Cardiff. That office was run by Captain Jack Harkness, the mysterious immortal man from the future. And then that office was destroyed, leaving Torchwood with no headquarters and not much of an official status.

All you really need to know about Captain Jack is: he's from the 51st century, he's traveled extensively around the universe, and he's lived for thousands of years. And due to some time-travel shenanigans, he can't die. He can't even get hurt. He's also bisexual and extremely happy about it.

And it would probably be helpful to know that Captain Jack is carrying around a lot of guilt and remorse. He got almost all of the staff of Torchwood killed. Including his lover, Ianto. And in order to stop a ruthless race of aliens who wanted humanity's children, Captain Jack slaughtered his own young grandson. These events may not be referenced in detail, but Captain Jack's regrets will no doubt come up.

Actually, there's lots more to know about Captain Jack, but chances are none of it will come up. Like, he had a brother named Gray, who was lost during an attack by alien invaders, and turned evil. He also had an ex-boyfriend, Captain John, who turned sorta-evil. He was an agent for the mysterious Time Agency, which erased two years of his memory. He fought in World War I, and about three versions of him were in World War II. He was attacked by fairies and joined the circus. Almost certainly, none of this stuff will be mentioned or even referred to, ever again. Forget we mentioned it.

Who else is in Torchwood, besides Captain Jack?

Lots of people who are dead. You don't need to know about them. Captain Jack's dead boyfriend, Ianto, may be referred to in passing. The other Torchwood dead will probably not even be alluded to.

Plus there's Gwen Cooper, who was a policewoman until she stumbled on the truth about Torchwood — and then she was recruited to join. She kept Torchwood a secret from her fiancé, Rhys, for a long time. But eventually Rhys found out, and became sort of an unofficial member, who complains a lot about the danger that Torchwood puts Gwen into. Gwen and Rhys got married, and Gwen got pregnant, with an apparently normal baby. Oh, and it's been hinted that Gwen and Jack are secretly in love with each other.

The Torchwood crew have been known to use lots of extraterrestrial technology to get around stuff. This includes Retcon, a drug that erases your short-term memory - and probably causes nasty brain damage, if you use it too often. And there are fancy contact lenses that can function as cameras and broadcast whatever you see onto a laptop screen - plus allow you to read whatever is typed on that laptop. There's also a resurrection gauntlet, that can bring the dead back to life for a short time, but that was apparently destroyed.

So with Torchwood's headquarters destroyed and most of its staff dead, the organization is pretty much non-existent. In 2009's Torchwood: Children of Earth miniseries, the Torchwood team was hunted down by the British government because the government wanted to keep some extraterrestrial child-trafficking secret. As a result, the Torchwood Institute was left pretty much radioactive, and lost whatever government support it had left.

Children of Earth ended with the grief-and-guilt-stricken Captain Jack leaving our planet to go off and explore the universe again. (We later glimpse him in some alien bar on what looks like a space station, on Doctor Who.) Gwen, meanwhile, appears to be settling down with her husband Rhys and her new baby.

So where does that leave Torchwood? It's basically a defunct organization, that almost nobody living knows about, and it's gone so far from its original mission of advancing the British national interest and hunting the Doctor, that it's no longer really abiding by its charter. But with the Doctor frequently off saving other planets — there are a lot of them, after all — there are times when our world faces a weird, extraterrestrial situation so extreme, it needs the help of specialists. And even with just two members, plus a husband and baby, that's Torchwood.